textproduct: Rapid City

KEY MESSAGES

- Except for Tuesday, very warm weather expected over the next 7 days - Except for Tuesday, near-critical fire weather conditions expected the next 7 days, primarily over northeastern WY/southwestern SD

UPDATE

Issued at 950 PM MDT Sun Aug 30 2026

33z surface analysis had cold front/outflow exiting the CWA via south-central SD. Water vapour loop had upper ridge centered over MO with upper low spinning over southern SK. 100kt jet streak ahead of it, which assisted today's severe weather. Overall, current forecast in good shape.

Tonight through next weekend, southwest flow aloft expected over the CWA as upper ridge slowly works it's way westward by the end of the week. Shortwave ridging Monday will bring quiet and dry weather. Very dry relative humidity expected over northeastern WY/southwestern SD, but winds will be on the lighter side. A shortwave trough will bring a slug of moisture through the CWA late Monday night/Tuesday manifesting itself as a cluster of shra/TS. Buoyancy/shear combination suggests convection should be relaxed. Temperatures Tuesday will be influenced by clouds/precipitation which is reflected in cooler high temperatures. Upper ridge/lower tropospheric warm air advection returns Wednesday with very warm weather expected into next weekend. Can't rule out some storms from time-to-time given pattern, but trending drier is the main message of ensemble guidance. These facts will increase the fire danger as the week progresses.

DISCUSSION

(This Afternoon Through Saturday) Issued at 1152 AM MDT Sun Aug 30 2026

Upper air analysis depicts upper shortwave over northern ID/southern SK. Water vapor imagery shows line of convection developing over central MT/WY and moving eastward. These storms will move into the CWA in the next several hours. Inverted-V soundings indicate damaging wind gusts will be the main concerns with these storms. Some gusts over NW SD could exceed 75+ mph. Right now, there's some uncertainty as to how far south these storms will extend and if they'll impact the Rapid City area.

Broad upper level ridge builds over the central/eastern half of the US for the beginning of the week. This will lead to continuing warm conditions over our CWA and mostly dry conditions, though afternoon storms are possible tomorrow and Tuesday. Deterministic models show the ridge strengthening later in the week, leading to much warmer conditions over western SD and northeastern WY with highs climbing into the mid to upper 90s by Wednesday and Thursday. In addition to the hot temperatures, the very dry airmass will lead to elevated to near-critical fire weather concerns.

AVIATION

(For the 00Z TAFS Through 00Z Monday Evening) Issued At 516 PM MDT Sun Aug 30 2026

An impressive outflow boundary/cold front combination is blasting across western SD early this evening with gusts around 45kts and brief MVFR VSBYS due to dust. Isolated strong/severe thunderstorms with local IFR conditions will continue along the boundary north of KPHP through 31/02z. Otherwise, expect VFR conditions through the period.

FIRE WEATHER

Issued At 1152 AM MDT Sun Aug 30 2026

Isolated high-based thunderstorms are possible across northeastern WY this afternoon and evening. Storms may produce lightning and gusty winds but not much precip. Elevated to near- critical fire weather conditions possible over much of the area tomorrow, especially over northeastern WY where humidities may drop to as low as 10%, however winds are expected to remain light.

Near-critical fire wx conditions are possible later this week in the Wed/Thu timeframe as a hot and dry airmass moves into the region. Afternoon humidities ranging from 10 to 20% and breezy southwest winds will lead to widespread near-critical fire weather concerns across northeastern WY into western SD.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.